The story continues on our 1954 Cadillac's cooling problem. Recapping, last month we had put on a new 15-pound radiator cap, a 180-degree thermostat, fan shroud, 6 blade flex fan and a 12" pusher cooling fan. This fan is a recommended addition by Cadillac for a/c cars. We experimented with this fan and found it was more efficient if sandwiched between the air conditioner condenser and the radiator, but all these things made very little difference the car was driving at 200 and 215 in traffic on a 100-degree day. We decided to separate our work into two categories: Internal and External engine work. Since the engine had no sign of water in the oil, ran smoothly, and no visible mist was coming out of the tail pipe, we decided to work on the external things first. The timing was right on at 2 1/2 degrees, but we found burnt points and a bad plug wire. These were replaced, along with a new condenser and distributor cap. The radiator was inadequate (three row, meant for a non-air car), so we had a new 6-row made by Danny Burnette at Chattown Radiator. It looks great and fit into our tight space perfectly, leaving the necessary 1" fan-2-radiator spacing, and aligned up with our new shroud. With the new radiator in place, we took the car out for a test drive. The temperature outside was 100 degrees. The Cadillac did run cooler, but not cool enough (210 in traffic, 198 on the road.) The car still had its original 4" thick a/c condenser and very little air could move through it, so we replaced it with a modern 1 1/2" thick one that allowed more air to flow through it and through the radiator. We tried an additional 10" fan on the condenser, but it made no difference and overloaded the electrical system, so we quickly removed it. The car now ran a few degrees cooler, but it was still too hot. At this point, we had completed our external work. "It was time to go in "! We ran a fluid test to check for cracks in the head or block, or blown head gasket. We bought out test kit at Nappa Auto Parts (compression leak block tester BK-700-1006). The test it simple. You drain down the coolant in the radiator approximately 1 1/2", start and warm up the car to open the thermostat, then insert the tester tube into the radiator and pour the supplied blue fluid into the tube, then wait ten minutes to see if the fluid turns yellow. This color would indicate exhaust in the coolant system, ours remained blue. Great! No cracks, no blown head gaskets. But what was the problem? Next we went to the water pump, removed it and compared it with a spare pump removed from our parts car. There was a difference! The impeller on the parts car was down on its shaft fitting closer to the housing, which would let it pump more water. This could make a difference...let's replace the pump and see! With the replacement water pump, everything hooked up and the pusher fan on, we were off. 98 degrees outside, the a/c on, and the running temperature was down to 188 on the road and 198 in traffic. That's more like it. We shut off the a/c and the running temperature dropped even more, to 185 and 195 in traffic. That's GOOD ENOUGH! I had never realized how critical the impeller to housing clearance was. Later that night, I was reading from "Cadillac Automobiles 1949-1959" by Brooklands Books, and saw that in 1955 (one year newer) Cadillac drive report, the company introduced a new water pump with 20% more water volume at speeds lower than 10 mph. There must have been a problem or they wouldn't have changed the pump. Although our car is running cool now, I will probably change to this pump later. It might tweak it down to 180! Many of you have written in with similar problems, and we know that overheating can be a frustrating problem, but with research, testing, a lot of patience, and help from your friends, it can be fixed. My thanks to Charles Butts at American Restorations, Danny Burnette at Chattown Radiator, and everyone that helped us work through and help us solve this problem. Keep 'em running cool and on the road. See you next month!